Ability To Follow Scent to Source

One of the questions I repeatedly get asked is, “Can the dog really follow scent back to source?” Another variation is, “How can the dog know to leave lingering odor (i.e., where the source once was) and move to where the source is now?” My reply has been is that if a dog did not have the ability to locate where the mouse had gone, as opposed to where it had been, dogs would have starved to death long ago! In support of that opinion, I’d like to direct my students, as well as others who have joined my FB Page, to read the results of a canine scent detection study conducted by the Auburn University in June 1999. The title of the document is the “Canine Detection Capabilities: Operational Implications of Recent R&D Findings,” by J. M. Johnston, Ph.D., Institute for Biological Detection Systems. The whole article can be found at:

It is a very good read and there are many thought-provoking determinations in this article. I don’t have the science background to say, unequivocally, that all that is said in this article is 100% accurate, but most of it makes sense to me based on what I have seen in the 20-odd years that I have been training scent-detection dogs. But, in answer to the above questions, I point you all to the following excerpt:

Of course, for dogs, vapor collection, signal processing, and detection cycle times are essentially instantaneous. This level of olfactory sensitivity plays a key role in the dog’s ability to use concentration gradient information to locate an odor source. It is reasonable to presume that a dog coming into contact with the periphery of a vapor plume will initially encounter only relatively low concentrations of target compounds. Although the means by which spatially dispersed variations in concentration guide rapid movement toward the odor source has not been studied, it is clear that they are extremely efficient in using this information. That is, minimal sampling effectively guides rapid locomotion to the odor source. All detection tasks require that dogs respond to the lowest detectable concentrations of the target odor because it is such initial samples that can then prompt them to move in directions that lead to higher concentrations. Although trainers and handlers tend to focus on the quantity of training aids used as defined by weight, dogs respond to training aids in terms of the vapor concentration of signature compounds, not weight. It is therefore important that all dogs are trained to pay attention to a range of concentrations, including even the faintest whiff of target odors, regardless of differences in search scenarios. The findings from these sensitivity studies suggest that this approach will make the best use of dogs’ impressive olfactory sensitivity.

Enjoy the rest of the article and continue to learn about these incredibly talented canine partners with whom we share our lives!!